The inventive concept relates to semiconductor devices. More particularly, the inventive concept relates to a package on package in which several semiconductor packages are stacked one atop the other.
Many of today's compact electronic devices require a high capacity to store data, for example, and an ability to perform many different functions. There are constant market demands to increase the functionality and capacity of these devices while keeping these devices highly compact or even miniaturizing these devices. To meet these demands, a system in package (SiP) has been suggested. An SiP is a semiconductor package in which a number of integrated circuits are stacked. Thus, the SIP is rendered extremely compact but the combination of the integrated circuits provides the device with a high capacity and an ability to perform multiple functions.
SIPs are being produced largely in two types: one is a multi-chip package (MCP) in which a number of semiconductor chips or dies are stacked, and the other is a package on package (POP) in which a number of individual semiconductor packages which have been separately assembled and electrically tested are stacked.
In the case of POPs, bumps of conductive material have been used to physically and electrically connect the stacked packages. However, it is difficult to stack an upper package on a lower package using such bumps because the bumps can not be fabricated tall enough to physically connect the packages while allowing for a pitch that is small enough to provide for the requisite number of electrical interconnections. For this reason, a through mold via (TMV) method has been developed in which the bottom package is provided with a mold layer encapsulating a chip, holes are formed in the encapsulant, and the holes are filled with conductive material that form via plugs constituting the physical and electrical interconnections. In the TMV method, however, the holes must be formed using a laser or a drill after the mold layer has been formed. Consequently, the TMV process used in fabricating a POP is relatively complex and time consuming and thus limits the productivity of the POP manufacturing process.